The disclosures herein relate generally to electronic test equipment and more particularly to a through connector circuit test apparatus.
Many electronic devices often include electronic assemblies such as printed circuit boards (PCB's) that have one or more electrical connectors. To ensure that the electronic assembly is properly assembled, a through connector test sequence may be used to verify the operation of the electronic assembly. In this type of test, a circuit test apparatus is attached to one or more connectors of the electronic assembly.
Due to manufacturing tolerances, the connectors are not always positioned at the same location. The inconsistent positioning of these connectors can adversely affect the ability to use an automated circuit test apparatus to test the device. To compensate for variations in positioning, certain circuit test apparatus is often designed to float and to be self-centering. The floating feature allows the connector to translate to accommodate slight misalignments between the test connector of the fixture and the connector of the assembly being tested. The self-centering feature ensures that the connector returns to a nominal position when the fixture is disengaged from the electronic device being tested.
U.S. Pat. No. 5,831,438 discloses a device for testing a connector which has a plurality of terminals, each one of the terminal being mounted in a respective terminal chamber. There is a flexing space adjacent to each chamber and a resilient tongue, biased into the chamber. The resilient tongue is moved into the space as the terminals are inserted and springs out of the space when they are fully within their respective chambers. The device has a plurality of testing units attached within a body which is movable toward and away from the connector. If at least one of the terminals is not fully inserted into its chamber, the body is moved backward away from the connector so that contact between the units and the terminals is not made.
U.S. Pat. No. 5,698,990 discloses a counterforce spring assembly for printed circuit board test fixtures. A number of counterforce spring assemblies are provided in an array between the top plate and probe plate of the test fixture. Each counterforce spring assembly includes a support cup residing in an aperture through the probe plate. A compression spring resides in the support cup and provides spring-biasing of the top plate to the probe plate during the testing cycle. Each counterforce spring assembly includes a circumferential flange to limit downward travel of the top plate toward the probe plate. Each assembly is small enough to fit between probe apertures corresponding to component leads of the device being tested. The counterforce spring assemblies can be freely placed underneath the top plate to provide even spring-biasing thereof to prevent bowing and bending of the top plate which often causes errors in the testing of printed circuit boards.
U.S. Pat. No. 5,461,326 discloses a test probe including a flexible membrane having an array of test probe contacts. The test probe is capable of softly and gently contacting pads on a device under test with a structure that effectively applies tension to the membrane while at the same time automatically leveling the membrane and removing distortions. A small pressure plate is bonded to the inner surface of the membrane behind the test probe contacts. A pressure post having a pointed or rounded end is pressed against the pressure plate and makes pivotal contact with the plate. A spring including an adjustment screw that axially adjusts the compression of the spring, applies pressure through the pivot point to the pressure plate and to the membrane at its test probe contacts. When the probe contacts are pressed against a device to be tested, the probe contacts and the pressure plate rotate about the pivot point of the pressure post. This action planarizes the test probe contact array and levels the test contact array while appropriately tensioning the membrane.
U.S. Pat. No. 5,159,265 discloses a pivotable spring probe that includes a housing having an opening including a plunger that is guided by the housing. The plunger is slidably movable between an extended position and a retracted position. A pivotable contact head is mounted on the plunger for making electrical contact with a conductive surface external to the housing. A spring is mounted on the bottom of the plunger for biasing the plunger toward the housing opening.
U.S. Pat. No. 4,357,575 discloses an improved testing fixture apparatus for use in accurately effecting temporary electrical connections with the test point zones of printed circuit boards or the like. The board to be tested is mounted upon a locator assembly that is shiftably receivable within the fixture. The fixture includes a centering and gripping mechanism operative in conjunction with a cooperative part carried by the contact bearing portion of the fixture. The centering and gripping mechanism automatically positions the locator assembly and printed circuit board in a predetermined location within the fixture. This positioning assures precise alignment of a contact with each of the test point zones of the printed circuit board to be tested. The positioning action of the mechanism and its cooperating part includes both a centering function and a gripping function therebetween. Both of the functions occur automatically in response to relative shifting of the portions of the fixture for respectively supporting the printed circuit board and the contacts toward each other into an operative relationship for affecting electrical connections between the test point zones of the printed circuit board and corresponding contacts of the fixture.
The floating and self-centering functionality of a test connector may degrade over time. After prolonged use, some conventional test connectors develop a positional bias which returns the connector to an offset, non-centered nominal position. As the test connector is not able to properly mate with the corresponding connector of the device being tested, the test apparatus of the device being tested is often damaged.
Accordingly, there is a need for a through connector circuit test apparatus that exhibits accurate and reliable floating and self-centering operation to overcome the shortcomings of previous test connectors.